The U.S. military may be pulling out of Iraq, but Iraqi Prime Minister Nouri al-Maliki is investing billions of dollars in U.S. weaponry that will maintain Baghdad's links with the United States for years to come.

That includes a nod from the White House for the purchase of a second batch of 18 Lockheed Martin F-16IQ fighter jets worth $2.3 billion.

Earlier this year Iraq ordered its first squadron of F-16s. The new buy will give it 36 of the supersonic, multi-role jets by around 2018.

The deal, managed by the Pentagon's Foreign Military Sales program, includes 24 Pratt and Whitney F100-PW-229 or General Electric F110-GE-129 engines. It also encompasses weapons systems, such as Raytheon's AIM-9L/M Sidewinder and AIM-7M Sparrow air-to-air missiles, conformal fuel tanks and targeting pods.

Deliveries of the initial F-16s aren't scheduled until 2014, about the time the first pilots complete advanced training, but they won't be fully operational until 2015-16.

"The F-16 is obviously a very complex weapons system," said Maj. Gen. Russell Handy, the senior U.S. Air Force officer in Iraq. "It's going to take a while to train pilots."

The second F-16 deal was finalized while Maliki visited Washington Monday and met with U.S. President Barack Obama to declare the nine-year U.S. presence in Iraq over.

Maliki, an Iraqi Shiite who has a 30-year association with Iran, favored keeping a U.S. military presence after the withdrawal's scheduled completion Dec. 31, in large part to counter Tehran's efforts to dominate its ancient enemy.

In that delicate endeavor, he must tread carefully to avoid jeopardizing his fragile Shiite-dominated coalition, which is highly vulnerable to Iranian intrigue.

So the wholesale switching from the Soviet and Russian weapons systems, along with some French jets and missiles, with which Saddam equipped the vast forces he maintained during his rule to U.S. hardware would seem to be one way of keeping links to Washington.

The weapons Maliki has in mind include up to 96 F-16s acquired in four installments over the years to give Iraq some heavy-duty striking power.

But building up a strong and effective air force from scratch -- Saddam Hussein's once-powerful air forces was trashed in the 1991 Gulf War and never recovered -- via the government-to-government Foreign Military Sales program will take seven or eight years at least.

Add to that the extensive training programs the acquisition of the F-16s, the Abrams main battle tanks and the whole panoply of U.S equipment entails and military relations with the Americans will, if all goes well, continue for years.

Dan Darling, Middle East defense specialist with the Forecast International consultancy in Connecticut, estimates that Iraq bought arms worth $8 billion by 2005.

Of that, American systems accounted for about $5.2 billion.

From 2005-11, the U.S. Department of Defense allocated some $10.6 billion toward equipping and training the Iraqi security forces, as well as providing the infrastructure.

By the time the U.S. withdrawal has been completed, the Americans will have handed over sprawling air bases, some as big as Iraqi cities, and some 400 other installations, as well as vast amounts of equipment and stores, to the Iraqis.

Darling said that reports in the Iraqi media indicate that further security force orders for U.S. equipment could total $26 billion, with $13 billion in FMS requests by 2013.

As things stand, U.S. commanders say the Iraqi security force, around 700,000 strong, are probably capable of handling internal security but are woefully unable to defend against outside aggression.

The most likely threat might come from Iran, possibly an offensive aimed at Iraq's southern oilfields, its economic backbone -- the reverse of what Saddam tried to do to the infant Islamic Republic in September 1980.

But there are other potential threats out there, such as Syria to the west and Turkey to the north, which has unleashed ground offensives and repeated airstrikes against Kurdish rebel havens in northern Iraq in recent years.

Much of the military links with the United States as of January will be in the hands of U.S. Army Lt. Gen. Robert Caslen. He's commander of the soon-to-be-disbanded NATO training mission but he's set to take charge of the $10 billion weapons program to be run out of the massive U.S. Embassy in Baghdad.