Nigerian authorities have arrested three Lebanese, who reportedly confessed they were Hezbollah operatives, after uncovering an arms cache amid what seems to be a surge of covert activity by the Iran-backed Lebanese movement.

The Nigerians announced the arrests Thursday, the day after Argentina's state prosecutor, Alberto Nisman, accused Iran. Hezbollah's patron, of establishing a network of sleeper cells across Latin America, and three weeks after two Iranians were jailed for life in Kenya for plotting attacks on Western and Israeli targets.

Also on Thursday, the U.S. State Department said there was a "marked resurgence" of international plots and attacks in 2012, most notably in Europe and Africa, by Hezbollah, the elite Al-Quds Force of Iran's Revolutionary Guards, or both.

"Iran and Hezbollah's terrorist activity has reached a tempo unseen since the 1990s," the State Department observed in its annual global terrorism report.

Iran's intelligence services, often employing Hezbollah which they helped to create in 1982, have been active against the United States and Israel in recent years as they seeking to retaliate for the systematic assassination of Tehran's nuclear scientists and the sabotage of its nuclear program.

Hezbollah has its own reasons, primarily to take revenge against Israel, which it blames for Feb. 12, 2008, assassination in Damascus, Syria, of their iconic military leader, Imad Mughniyeh.

On May 6, Two Iranian nationals suspected of belong to the al-Quds Force, the Revolutionary Guards covert external operations arm which often works with Hezbollah on foreign operations, were sentenced to life imprisonment in Kenya for plotting attacks against U.S., British and Israeli targets in Nairobi.

When they were arrested in June 2012 they led authorities to a cache of 33 pounds of RDX, a powerful military-grade explosive, hidden near a golf club at the Indian Ocean city of Mombasa. Another 185 pounds of the RDX is missing.

In Nepal, Israeli Embassy personnel in Kathmandu seized an Iranian carrying a forged Israeli passport "acting suspiciously" at the embassy and handed him over to security authorities.

The Iranian, Mohsin Khosravian, had lived in Bangkok since 2004 and acquired the fake Israeli passport in Kuala Lumpur, Malaysia.

It wasn't known whether he was linked to attempted attacks on Israeli targets in Thailand and other Asian cities by an Iranian cell. Several were arrested in Bangkok in early 2012.

Thailand seems to have been a primary target for Hezbollah. Hussein Atris, a Lebanese holding a Swedish passport, was detained in Bangkok in January 2012.

Swedish media say he ran a hairdressing salon in the Swedish city of Gothenburg and married a Swedish woman in 1996. One of his relatives, Mohammad Atris, was involved in the Iranian-led assassination of four Kurdish opposition figures in a Berlin restaurant in 1992.

Thai police said Hussein Atris had an accomplice and issued a composite portrait that bears a striking resemblance to a notorious Hezbollah operative known as Naim Haris. Israeli intelligence says he's in charge of recruiting Hezbollah agents worldwide.

On Feb. 20 a court in Cyprus sentenced Hossam Taleb Yaacoub, a 24-year-old Lebanese with Swedish citizenship, to four years in prison for helping Hezbollah plot attacks against Israeli tourists on the Mediterranean island.

Yaacoub, who confessed he was with Hezbollah, was arrested in July 2012, about the same time that five Israeli tourists were killed in a bombing in the Bulgarian Black Sea resort of Burgas in an attack that appeared to be similar to the one Yaacoub was scouting out.

The Burgas bomber, identified by police as a Hezbollah activist, was also killed but it's not clear whether the attack was planned as a suicide bombing.

Bulgarian authorities say two other Lebanese-born Hezbollah members, traveling on genuine Australian and Canadian passports, escaped to Lebanon.

Several of these cases involve suspected Hezbollah operatives using fake or genuine Western passports, suggesting they were recruited because they had lived in Western countries and obtained citizenship or had been trained to operate in Western society under false identities.

Hezbollah formed a special group in the 1990s that recruited such operatives, including fair-skinned Lebanese who could pass as North Americans or Europeans.

One graduate infiltrated Israel on a bombing mission using a Western identity. But he blew himself up in a Jerusalem hotel while he was assembling his bomb.

Syria: Hezbollah triumphs, but loses veterans
Beirut, Lebanon (UPI) May 30, 2013 - Hezbollah fighters played a key role in defeating Syrian rebels in the strategic crossroads town of Qusair, but the Iranian-backed Shiite movement reportedly lost many battle-seasoned veterans of its war against Israel.

The escalating role in the Syrian conflict, supporting longtime ally President Bashar Assad against rebels battling to topple his regime, is becoming a gamble for the Shiite movement that could weaken its campaign against Israel and its standing in Lebanon.

The rebel Free Syrian Army claims 7,000 Hezbollah fighters are deployed in Syria. There's no way to verify that, but a force that size would involve most of Hezbollah's military wing despite a major recruitment drive after the 2006 war with Israel.

That seems unlikely since it would presumably mean pulling combat forces out of the Israel front in south Lebanon.

French Foreign Minister Laurent Fabius says France's intelligence service estimates 3,000-4,000 Hezbollah fighters are in Syria.

Some 1,700 were involved in the battle for Qusair that began May 19, when regime forces launched a major assault on the rebel-held town in western Syria, Lebanese security forces said. Hezbollah has been tight-lipped about its casualties, which suggests they may have been much higher than anticipated.

Two senior field commanders were reported killed in Qusair. Lebanese sources identified them as the commander of the Al-Quds Brigade, known by his nom de guerre of Abu Ajib, and his deputy Hamza Ramloush.

One Hezbollah fighter, who was in action until May 25, told reporters in Beirut the movement had lost about 100 killed in Qusair. But he said "we'd planned for as many as 1,000 martyrs" because the rebels were well dug in on their own ground.

Hezbollah initially denied its military wing was fighting in Syria and sought to bury its dead unobtrusively. But it's been forced to admit it's heavily engaged.

Now the extent of its casualties are becoming known, some in the movement question why it should be fighting fellow Arabs in Syria when its main mission has always been battling Israel.

And while there have long been differences within Hezbollah between pro-Syria and pro-Iran factions, party leader Hassan Nasrallah says the movement will become totally isolated if Assad's toppled and its arms supply route from Iran is severed.

Even so, fighting in Syria is a big gamble for Nasrallah. If Hezbollah is isolated, it would be caught between rival Sunni militants, including al-Qaida, and Israeli forces, and many Lebanese who blame it for dragging the country into wars that were not of their making.

It is clear Hezbollah's commitment of a sizeable combat force was the decisive stroke that allowed Assad to effectively seize Qusair.

Hezbollah's fighters are highly disciplined and well-trained by Iran, particularly the elite al-Quds Force, the Revolutionary Guard Corps' largely covert foreign operations arm which is closely involved in bolstering Assad's forces.

Indeed, Hezbollah's configured more as a conventional military force than the sectarian militia that's long been its image. It's also had more experience in urban fighting that Assad's regulars, which is why, after a string of tactical advances, it was made the spearhead of the assault on Qusair.

Most of Hezbollah's casualties were inflicted in the opening stage of the offensive, Lebanese security forces said. At one point, a 200-man assault force was badly mauled in an elaborate bomb ambush by the rebels and lost at least 18 killed and dozens wounded.

Elite Hezbollah units were then sent in to rally the attackers and pushed deeper into Qusair despite fierce opposition.

The mounting losses may intensify pressure on Nasrallah to ease off, not just for political reasons but because the casualties will erode Hezbollah's military capabilities, particularly against Israel.

It's generally accepted that Hezbollah lost 500-600 fighters during the 34-day war with Israel in 2006.

That was deemed a significant percentage of its fighting force at the time, around 2,000 hard-core regulars.

It has greatly increased recruitment since then, maintaining a larger force.

"A high casualty rate of newly trained 'elite' fighters, recruited to replace those killed in 2006, means a waste of precious time and resources," observed analyst Tony Badran of the Foundation for Defense of Democracies.

"The loss of even more battle-hardened soldiers, on top of the 500-600 men from 2006, means further loss of operational memory and combat experience in the party's fighting corps."