Defoe has been in lethal form for his relegation-threatened club, scoring 14 of the Black Cats' 24 league goals this season but last appeared for England in November 2013 when he won his 55th cap.
"I didn't want to just look at his age and think he's finished with England," manager Gareth Southgate told reporters.
"I think you get young players with a point to prove and older players with a point to prove. I think he still feels that. I think he warrants the call-up."
England play Germany in Dortmund next Wednesday and Lithuania at Wembley on March 26.
Southgate said he had to look at the near term as well as long, even if England were "nodding towards the future" with some of the decisions.
"You need senior players within that to educate some of the younger ones, to show them some of the things they need to learn and also the competition's important," he added.
Southgate did not rule out Defoe for next year's World Cup finals in Russia, saying all of the players faced competition for their places.
"It can't be a comfortable environment where people think they are going to be in every time," he said.
Striker Harry Kane, who damaged ligaments in Tottenham Hotspur's 6-0 FA Cup quarter-final win over Millwall last weekend, is absent as was Manchester United's Wayne Rooney.
Southgate said he had talked with Rooney, who has recovered from injury, but his lack of recent game time told against him.
Defoe is the top English scorer in the Premier League after Kane, who has 19 goals to his credit.
Goalkeepers: Fraser Forster (Southampton), Joe Hart (Torino, on loan from Manchester City), Tom Heaton (Burnley)
Defenders: Ryan Bertrand (Southampton), Gary Cahill (Chelsea), Nathaniel Clyne (Liverpool), Phil Jones (Manchester United), Michael Keane (Burnley), Luke Shaw (Manchester United), Chris Smalling (Manchester United), John Stones (Manchester City), Kyle Walker (Tottenham Hotspur)
Midfielders: Dele Alli (Tottenham Hotspur), Michail Antonio (West Ham United), Ross Barkley (Everton), Eric Dier (Tottenham Hotspur), Adam Lallana (Liverpool), Jesse Lingard (Manchester United), Jake Livermore (West Bromwich Albion), Alex Oxlade-Chamberlain (Arsenal),Nathan Redmond (Southampton), Raheem Sterling (Manchester City), James Ward-Prowse (Southampton).
Forwards: Jermain Defoe (Sunderland), Marcus Rashford (Manchester United), Jamie Vardy (Leicester City)
(Reporting by Alan Baldwin, editing by Neville Dalton)
