US vs Iran
“The Basij (Mobilization of the Oppressed) is a popular reserve force of about 90,000 men with an active and reserve strength of up to 300,000. “On paper, the Basij has over 2,000 battalions, each supposedly of some 500 troops (including some women's battalions). Although equipped almost exclusively with small arms, most Basij battalions have apparently been reasonably well- trained and some select units may be comparable to regular light infantry. In addition to the "active" Basij, numbering on paper about 1,250,000 men and women, there are supposedly some 2 million more inactive militia members, though they are usually older personnel, and often lack equipment. About a third of the Basij are well enough trained and led to be ready for active service in days.” 
Iran also has 45,000-60,000 men in the Ministry of Interior serving as police and border guards, with light utility vehicles, light patrol aircraft (Cessna 185/310 and AB-205 and AB- 206s), 90 coastal patrol craft, and 40 harbour patrol craft.”  Iran's military also includes holdings of ca 1,700 main battle tanks, ca 1500 other armoured fighting vehicles, ca 3,000 artillery weapons, 200 to 300 combat aircraft, around 340 helicopters, 3 submarines, 56 surface combat vessels and around 160 patrol crafts. Here I have to emphasise that none of the available statistics are reliable. Iranian government does not release proper statistics on its armed forces and many of its acquisitions especially locally manufactured armaments remain a secret. It is therefore extremely difficult to say, with any degree of certainty that the above stated statistics are even close to the mark.
Dr. Abbas Bakhtiar