White House presses Iraq to block Iranian aid to Syria

 Baghdad must step up its efforts to block Iranian shipments of weapons and aid moving through Iraqi airspace to Syrian forces loyal to embattled President Bashar Assad, the White House said Wednesday. 

"We would like [Iraq] to do more" to rein in or cut off Syrian supply lines running from Tehran, a senior administration official told reporters. 

Specifically, the Obama administration is pressuring Iraqi Prime Minister Nouri al-Maliki to focus on patrolling the air routes used by Iranian forces to smuggle arms and supplies into Syria. 

Iranian supply routes, along with the growing al Qaeda threat in Iraq and Syria, is at the top of the agenda for Maliki's visit to Washington this week. 

The Iraqi delegation met with Vice President Joe BidenJoe BidenJames Carville: Biden represents 'stability' not 'generational change' Trump's misspelling of Biden's name trends on Twitter Trump says 'I have confidence' after past North Korea missile tests MORE Wednesday morning, and will meet with congressional leaders later in the day. 

The White House and Congress have repeatedly voiced their concerns over Iraq's ability to block Iranian aid shipments since the beginning of the Syrian civil war three years ago.

"We are greatly disturbed that as the international community works to bring peace to Syria, the Iraqi government is not doing everything in its power to prevent the slaughter of thousands of innocent civilians," Reps. Ted Deutch (D-Fla.) and Tom CottonThomas (Tom) Bryant CottonGOP senator says Iran needs to 'stop acting like an outlaw' Sen. Tom Cotton: 'Memorial Day is our most sacred holiday' The Hill's Morning Report — After contentious week, Trump heads for Japan MORE (R-Ark.) wrote in a letter to Maliki in March. 

On Tuesday, Sen. John McCainJohn Sidney McCainClimate change is a GOP issue, too It's Joe Biden's 2020 presidential nomination to lose Meghan McCain on Pelosi-Trump feud: 'Put this crap aside' and 'work together for America' MORE (R-Ariz.) along with Senate Armed Services Committee chief Carl LevinCarl Milton LevinListen, learn and lead: Congressional newcomers should leave the extremist tactics at home House Democrats poised to set a dangerous precedent with president’s tax returns The Hill's 12:30 Report — Sponsored by Delta Air Lines — White House to 'temporarily reinstate' Acosta's press pass after judge issues order | Graham to take over Judiciary panel | Hand recount for Florida Senate race MORE (D-Mich.), ranking member Jim InhofeJames (Jim) Mountain InhofeTrump defense pick expected to face tense confirmation Overnight Defense: Details on Senate's 0B defense bill | Bill rejects Trump plan to skirt budget caps | Backfills money for border wall | Defense chief says more troops could head to Mideast Senate panel rejects Trump plan to skirt budget caps, advances defense bill that backfills wall money MORE (R-Okla.) rasied the issue again in a letter to President Obama, ahead of Maliki's visit to Washington. 

"We urge you to make clear to Prime Minister Maliki that the extent of Iran’s malign influence in the Iraqi government is a serious problem in our bilateral relationship, especially for the Congress," according to the letter. 

Senate Foreign Relations heads Sens. Robert MenendezRobert (Bob) MenendezEnding the Cyprus arms embargo will increase tensions in the Eastern Mediterranean We can accelerate a cure for Alzheimer's The Hill's 12:30 Report: Manafort sentenced to total of 7.5 years in prison MORE (D-NJ) and Bob CorkerRobert (Bob) Phillips CorkerJeff Daniels blasts 'cowardice' of Senate Republicans against Trump Corker: 'I just don't' see path to challenge Trump in 2020 Ex-GOP Sen. Corker: Trump primary would be 'good thing for our country' MORE (R-Tenn.) also co-signed the letter. 

That said, "policing this is extremely difficult . . . [and] its really an ongoing effort" between Washington and Iraq to shut those supply lines down, the White House official said. 

During the bloodiest days of the Iraq War, U.S. and coalition forces were unable to block similar weapons and supplies shipments from Iran to insurgent groups inside the country. 

For its part, Maliki's government argues it does not have the airpower necessary to ward off the Iranian air shipments. 

To that end, Maliki told reporters in Baghdad he will press the White House to accelerate sales of F-16 warplanes and possible sales of unmanned aircraft to Iraq. 

Washington and Baghdad inked a deal in August to provide Iraq's nascent military with the American jets. 

Without those air assets, Baghdad claims its airspace will remain indefensible to Iranian supplies and support.