U.S. lawmakers said on Monday they wanted another $18.5 billion...

U.S. lawmakers said on Monday they wanted another $18.5 billion added to President Donald Trump's proposed defense budget of $603 billion to hire more troops and buy more aircraft and ships in fiscal 2018.

Republican House of Representatives Armed Services Committee Chairman Mac Thornberry released a proposed defense policy bill intended to address military readiness and the Department of Defense's unfunded requirements list, which is hovering at $33 billion, House staff told reporters on Monday.

The $621.5 billion proposed base spending plan for the Pentagon and defense related expenses at the U.S. Department of Energy was more than 13 percent higher than the 2018 defense spending budget cap of $549 billion which would need to be raised by Congress for the legislation to be enacted.

The proposal also included $75 billion for Overseas Contingency Operations (OCO) to pay for ongoing wars. This funding would not count against the budget caps. The House proposal would put total defense-related spending at $696 billion for fiscal 2018.

Trump's budget proposal included $65 billion for OCO funding, and total spending of $668 billion.

If enacted, the House proposal would mean the Pentagon could commit to buying 17 more F-35 jets from Bethesda, Maryland-based Lockheed Martin Co LMT.N for a total of 87 in 2018.

It would increase the Army by 10,000, to 486,000 active service troops.

The proposal would allow the Pentagon to buy a total of 22 Boeing Co BA.N F-18s, up from 14 in Trump's budget proposal.

The proposal also gives the Navy authorization for an additional five ships above Trump's original budget request. The ships include an Arleigh Burke class destroyer made by General Dynamics Corp GD.N and Huntington Ingalls Industries Inc HII.N and a total of three Littoral Combat Ships built by Lockheed Martin and Australia's Austal Ltd (ASB) .

The proposal also includes defense acquisition reform measures that would change how the Pentagon buys services and would allow the military to buy commercial off the shelf products from existing business to business e-commerce markets, such as Amazon.com Inc AMZN.O or W W Grainger Inc GWW.N .

On Wednesday, Democrats and Republicans on the House Armed Services Committee are slated to meet to discuss and potentially alter the proposal.