It is a common mistake to think that the president of the US can declare war. This is incorrect.
According to the U.S. Constitution, only Congress has the power to declare war on another sovereign nation.
According to Article I , Section 8: "The Congress shall have Power ... To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years; To provide and maintain a Navy; To make Rules for the Government and Regulation of the land and naval Forces; To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions; To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress ...".
However, the resolution in Congress must pass both the House and Senate, the President has the authority to either sign or veto the resolution. The ONLY times that a binding act of Congress does not cross the President's desk are: I) A Constitutional Amendment II) Articles of Impeachment, or a subsequent conviction or acquittal in the Senate. III) Confirmation of appointees. Historically the President has always asked Congress for an official declaration of war before Congress passes such a resolution, although this is not necessary.
Other than the War of 1812 and the Spanish American War, Congress has overwhelmingly voted in the affirmative, therefore a Presidential veto would be toothless, even if he desired to do so.
The US President does have the power to deploy troops to said
The US Constitution says the Congress has the power to declare war