Israel and China have been renewing military ties in recent months after a lengthy chill caused by hefty Israeli arms deals that the United States shot down.

The upswing in relations between the defense establishments has raised eyebrows in Washington, which views China's expansion in the Pacific with growing concern.

Israel once seemed set to be a major arms supplier to China. But in 2000 they fell out after the United States, Israel's strategic ally which provides $3 billion in military aid a year, pressured the Jewish state not to sell a sophisticated airborne early warning aircraft to Beijing.

But in recent months, relations have begun warming again and in 2010, Beijing invited the commander of Israel's navy, Adm. Eliezer Marom, to visit.

Marom's mother was Chinese, so the belief in Israel's Defense Ministry was that Beijing was seeking to restore defense links with Israel.

"While the ban on Israeli defense exports appears to still be in place," observed Yaakov Katz, defense editor of The Jerusalem Post, "there is no question that Israeli-Sino military ties have entered a new period of warmth -- although the content of those ties largely remain a mystery."

That seems evident from a recent flurry of high-level bilateral visits by senior military officials from both countries, although there's no sign that China will resume buying Israel arms -- yet.

In May, Israel's military chief of staff, Lt. Gen. Benny Gantz went to Beijing for talks with top officials of China's defense establishment.

That returned an August 2011 visit to Israel by Gen. Chen Bingde, chief of the general staff of the People's Liberation Army, the first by a Chinese military chief. Two months before Bingde's visit, Israeli Defense Minister Ehud Barak traveled to China, the first Israeli of that rank to do so in a decade.

Before that trip, Barak met with Adm. Wu Shengli, commander of the Chinese navy when he visited Israel.

In the summer of 2010, Maj. Gen. Yair Golan, then head of Israel's Home Front Command, led an Israeli military mission to Beijing a few months after Maj. Gen. Amos Yadlin, then head of Military Intelligence, flew to Beijing with Deputy Prime Minister Moshe Yaalon.

Now, Israeli Prime Minister Binyamin Netanyahu is reported to be planning a visit to Beijing himself.

In the meantime, Maj. Gen, Matan Vilnai, a former deputy chief of staff, is Israel's new ambassador to China.

Amid the raised eyebrows in Washington, where U.S. President Barack Obama is building up U.S. forces in the Pacific while withdrawing troops from Iraq and Afghanistan, Katz observed: "Israeli officials are quick to stress that all the visits -- whether to Israel or China -- are first cleared with the United States."

Israel's military ties with China flourished in the 1980s and 1990s, mainly through Israeli upgrades of China's Soviet-era platforms. Israeli companies had become experts in modernizing Soviet equipment because of the large amounts of such weaponry captured from Arab forces in the 1967 and 1973 Middle East wars.

Major contracts with Beijing looked likely. In May 1997, Israel agreed to sell China an EL/M-2075 Phalcon airborne early warning aircraft, a converted Russian Ilyushin Il-76, built by state-run Israel Aircraft Industries -- now Israel Aerospace Industries -- under a deal valued at $1 billion.

In July 2000, Israel was forced to cancel the deal under heavy pressure from the United States, which claimed the Phalcon could track U.S. aircraft if hostilities broke out over Taiwan. U.S. congressional leaders threatened to cut $2.8 billion in aid to Israel if the deal went through.

The cancellation was a major blow to China's military modernization program. Beijing demanded $1.26 billion in compensation but in February 2002 settled for $350 million.

Then in late 2004, Israel fell foul of Washington over a $70 million 1994 contract with China under which it supplied IAI-built Harpy combat drones, which are designed to destroy radars.

When China sent some Harpys to Israel for upgrading, Washington claimed U.S. systems were being installed and U.S. officials threatened to cut Israel out of Lockheed Martin's Joint Strike Fighter program if the upgrades were carried out.

Israel complied and in 2005 agreed to allow the U.S. to veto its arms sales to China and other countries that Washington deemed could compromise U.S. security.